A few years back we installed an APEC RO90 and it has worked flawlessly. We moved out to the country, installed another RO90 on the "city" water and it again performed great. Now we want to take it up a notch and try to go self sufficient and get away from all the chemicals/downside of public water. We drilled a well, but sulfur was too high consider treatment. We have a large spring on the property and a water test showed clean from industrial chemicals (as you would expect out in the country). The two negatives we have is that the water is a typically hard for limestone country at 121 mg/L (CaCO3) and the tests for E.coli/Coliform came back positive. Water from the "city" source is similarly hard, so my only real problem is the pathogens. (Chlorinating puts me back in the starting position with getting rid of chemicals and UV's maintenance/longevity issues rule that option out for us.) From what I have read, a good RO membrane can take out these pathogens. (In fact, recurring bouts of intestinal ailments got me to install the original RO90 system at the first house ... and that worked wonders for me ... and lowered my confidence in "big city" water noticeably. Especially after I found out that the city water intake was just downstream from the city dump leachate treatment plant. [B]:^([/B] I have researched Dow Filmtec/Axeon/other membrane manufacturers and they make membranes that range upwards of 2500 to 10,000 gallons per day. Pricey, but not impossible with a little savings/elbow grease. I have looked at a number of "commercial" plug and play systems in the range to deliver 5 gal per minute that use these larger RO cartridges, but they are loaded with pumps/controllers/instrumentation that moves the price to the stratosphere. Our need here is to come up with the most straight forward design that a 50 year DIY guy with time on my hands can build from off the shelf membranes/housings/etc. Would be interested to hear from anyone that might suggest practical design resources or may have done a similar project. Thanks! M

When I run the sink water, I hear a gurgling sound every 10 seconds from the bath drain. On looking below (ceiling space of the floor below), I see 2 pipes going into one 2" waste pipe. The one under bath has a p trap. The sink p trap is directly under the sink in the sink vanity/closet. Is it possible the sink is syphoning the bath somehow?